Stefanos Tsitsipas will become Greece's first Grand Slam champion and a world number one if he wins the Australian Open final on Sunday -- he will have his father to thank if he does.

There are not many athletes whose careers and outlooks have been forged by near-death experiences, but the 24-year-old world number four is an exception.

In 2015, while taking part in a third-tier event in Crete, a teenage Tsitsipas and a friend went swimming and almost fatally misjudged the strength of the currents.

The two boys were just moments from being swept away until Tsitsipas's father Apostolos, who is also his coach, dived in to haul them to safety.

"We couldn't breathe, I felt awful to be inside the water and was terrified. I didn't know how all this was going to end," Tsitsipas once recalled.

"My father saw us from afar and he jumped in, started swimming towards us and pushed us towards the beach. I was just a few breaths away from dying.

"If we were supposed to die and lose our lives that day, we would have to do it together. My father was a hero.

"That was the day I saw life with a different perspective. I remember after that how much psychologically it changed me."

Tsitsipas shares the same birthday as Pete Sampras -- August 12 -- and is studious, contemplative.

He speaks Greek, English and Russian, and has dabbled in Spanish and Chinese.